Accumulator



w. H. PEE-|- AccUMuLAToR Aug. 4, 1964 Filed NOV. 27, 1961 INV EN TOR.

United States Patent O 3,143,144 ACCUMULATOR William Harold Peet, 2115Devonshire Road, Ann Arbor, Mich. Filed Nov. 27, 1961, Ser. N0. 155,101'7 Claims. (Cl. 13S-30) This invention relates generally to accumulatorsand refers more particularly to accumulators of the ilexible diaphragmtype.

An essential object of lthe invention is to provide an accumulator ofsimple and inexpensive construction of the type having a ilexibletubular diaphragm disposed coaxially within an elongated cylindricalcasing, in which an improved internal backing core structure is providedfor the diaphragm.

Another object is to provide an accumulator having increased volumetricelliciency.

Another object is to provide an accumulator having a diaphragmsupporting core the periphery of the convoluted section of which isapproximately equal to the inside circumference of the diaphragm tube inits free state.

Another object is to provide a core which is constructed to bettersupport the flexible diaphragm tube with less stress, contributing tolonger life of the diaphragm tube.

Another object is to provide a valve construction for the core havingbetter liquid llow characteristics.

Another object is to provide an accumulator having a core provided withports for the ilow of fluid into and out of the core, the core beingconstructed to close and fill the ports in response to the collapse ofthe diaphragm tube so that the tube will not extrnde into the ports.

Another object is to provide an accumulator having a core includingconfronting Walls relatively movable toward and away from each other,the walls being adapted to support on their outer surfaces spacedportions of the tube when collapsed and to be moved toward each other toa limiting position by the pressure of the collapsed tube, ports in oneof the walls for the ow of Huid into and out of the core, and elementson the other Wall respectively opposed to the ports and operative toenter and substantially completely ll the ports upon relative movementof the walls toward each other to the limiting position.

Another object is to provide an accumulator wherein the outer surface ofthe other wall referred to in the preceding paragraph is smooth and theouter surface of the aforesaid one wall is smooth except for the portstherein, the ends of the elements on the other wall being disposed flushwith the outer surface of the one wall in the limiting position of thewalls.

The foregoing as well as other objects will become more apparent as thisdescription proceeds, especially when considered with the accompanyingdrawing wherein:

FIGURE l is a longitudinal sectional view of an accumulator embodying myinvention.

FIGURE 2 is an enlarged fragmentary perspective view of the coreemployed in the accumulator shown in FIG- URE 1.

FIGURE 3 is an enlarged sectional view taken on the line 3-3 of FIGURE land showing the core in its normal free state permitting the flow offluid into and out of the core.

FIGURE 4 is a view similar to FIGURE 3 but showing both the diaphragmtube and core collapsed.

FIGURE 5 is an enlarged fragmentary sectional view of a portion of thestructure shown in FIGURE 4.

Referring now more particularly to the drawing, the accumulator isgenerally designated and comprises a rigid outer cylindrical casing 12which is internally 3,143,144 Patented Aug. 4, 1964 ICC threaded at bothends. Discs 14 and 16 are threaded into the ends of the cylinder toclose the same.

A flexible diaphragm tube 18 which in its normal free state ispreferably of uniform circular cross-section throughout its length isdisposed within the cylinder 12 and extends from `one end disc to theother. The diaphragm tube is formed of rubber `or like material, and inits free state has a diameter somewhat less than the inside diameter ofthe cylindrical casing 12. The diaphragm tube 18 is shown in its freestate in FIGURE 3, and While it does not appear to be of true circularoutline, it will be understood that this is because the walls of thetube have attened out or sagged somewhat between the lobes of the coredescribed more fully hereinafter. With further reference to theconstruction of the diaphragm tube, it will have, in its free state,straight walls in longitudinal Section.

Extending within the exible diaphragm tube 18 is the core 20 provided tointeriorly support the tube. The core is of the tubular constructionshown, its ends being circular and formed with the annular grooves 22which are adapted to receive the beads 24 on either end of the tube. Thebeads of the tube are accordingly clamped between the grooves 22 of thecore and the inner surface of the casing 12, and the bead ends of thetube are only slightly stretched, if at all.

Referring to FIGURES 2-4, it will be seen that the cross-section of themajor intermediate portion of the core forms the three lobes or tubularportions 26, 28 and 30 which are spaced 120 apart and are parallel toand displaced radially equal distances from the central longitudinalaxis of the casing 12. The core has the central portion 32 bridging thespace between the tubular portions or lobes 26, 28 and 30 which hasexternal surfaces shaped to blend smoothly with the external surfaces ofthe tubular portions for the uniform support of the tube when collapsedwithout sharp bends.

Actually as seen in the drawing, the central portion 32 includes thepairs of confronting walls 34, 36 extending from the tubular portion 26,the pairs of confronting Walls 38, 40 extending from the tubular portion30, and the confronting walls 42, 44 extending from the tubular portion28. These Walls for the major part of their length are ilat planarportions of the core. However, near either end of the core the walls34-44, as well as the tubular portions 26-30, blend smoothly into thecircular form of the core. This can be best seen in FIGURE 2.

The core may be formed from an initial tube of uniform circular outlinethroughout its length corresponding generally to the circular form ofthe core shown at either end. The nodal form of the core between itsends is formed by deforming the intermediate portion of the initialtube.

A bolster reinforcement is provided at either end of the accumulator.The bolster reinforcements are designated 46 and 48 and are of the sameexterior form and are confined within the casing 12 by end discs 14 and16. They are provided to interiorly support the ends of the core andhave a special surface contour designed to conform with the interiorshape of the core at its ends and partially into the portions thereofjoining the intermediate nodal portion. The bolster 46 is provided witha chamber 50 which is in communication With the port 52 in end plug 14.The port 52 is adapted to be connected to a source of hydraulic fluid inthe line to which this accumulator is designed for connection. Leadingfrom the chamber 50 are the three passages S4 which respectively openinto the tubular portions 26, 28 and 30 of the core. Hence there is afree communication of hydraulic fluid into and out of the tubularportions of the core through the chamber 50 and passages 54 in thebolster 46. The other bolster 48 may be of solid construction.

The core is formed of a flexible resilient metal such as steel and isshown in its normal free state in FIG- URE 3, in which the opposed pairsof walls of the central portion 32 thereof are spaced from each other sothat there is a free communication of hydraulic uid between the tubularportions 26-34) at this time.

A longitudinally spaced series of ports 56 is provided in each of thewalls 36, 38 and 42. In each of the confronting walls 34, 40 and 44there is provided a longitudinally spaced series of valve-like elements58. The valve elements 58 are respectively opposed to the ports 56 andmay be formed by deforming or depressing the metal of the wallsthemselves, as shown. The valve elements S are generally frusto-conicalin shape, and the ports in the opposite walls are of a complementaryfrusto-conical shape adapted to provide a full surface seatingengagement with the valve elements when they enter the ports (FIGURE 5).It will be noted that the concave sides of the valve elements are filledwith a solder 59 or similar material to preserve the fiat smooth surfaceon the outer sides of the walls.

A suitable charging structure 60 is provided for filling the chamberdefined between the diaphragm tube and casing with air under pressure.The charging structure comprises a cylindrical housing 62 welded orotherwise permanently secured to the exterior surface of the cylinder 12over an opening in the wall of the cylinder. A rubber plug 64 fills theopening in the cylinder wall. Within the housing 62 is a disc 66 havinga tapered through passage overlying the plug 64. A screw cap 68 threadsinto the upper end of the housing d2 to conne the disc 66, and isprovided on its underside with a complementary tapered projection 70formed to enter and iiil the tapered passage in the disc so that thelower small end of the projection lies ush with the under surface of thedisc and engages the rubber plug.

To charge the accumulator with air, the screw cap 63 is removed and ahypodermic type air injection needle is inserted into the taperedpassage in disc 66 and through the plug 64. Air under pressure is thenadmitted to the space surrounding the tube 18 via the needle to chargethe accumulator. Thereafter, the needle is removed and the cap 63replaced. The hole pierced in the plug by the needle automatically sealsitself when the needle is withdrawn. The time interval between removalof the needle and replacement of the cap 68 is not enough for the rubberplug 64 to extrude through the small tapered passage in the disc 66.However, since in time the rubber of the plug would extrude through theextremely small diameter tapered passage, the projection 7) on the cap68 is provided to fill the passage.

FIGURE 4 illustrates the diaphragm when collapsed. This occurs when thepressure of air surrounding the tube exceeds the hydraulic pressureinside the tube. Under these circumstances, the tube gradually collapsesfirst about the tubular portions 26-30 and then inwardly andprogressively along the walls of the central portion 32. At final fullcollapse, the walls of the tube even press against the walls of thecentral portion near their junction at the axis of the core. As the tubethus collapses progressively radially inwardly, the confronting Walls ofthe central portion are flexed toward one another, and the valveelements 5S gradually enter ports 56. Actually, the walls of the centralportion of the core begin to move toward one another While the tube isstill collapsing only around the tubular portions 26-30, that is, beforethe tube actually engages the walls of the central portion ofthe core.

FIGURE 4 shows the tube fully collapsed at which time the confrontingwalls of the central portion are actually in surface-to-surfaceengagement with each other, defining the limit of movement of such wallstoward one another. At this time, the outer at surfaces 70 of the valveelements are disposed ush with the outer surfaces of the walls of thecentral portion in which the ports are formed and the frusto-conicalsurfaces of the valve elements are seated in full surface-to-surfaceengagement with the frusto-conical complementary surfaces defining theports (FIGURE 5). Hence the ports are fully closed and extrusion of therubber tube into the ports is effectively prevented. When the hydraulicpressure increases and forces more liquid into the core, the core willbe permitted to expand enough so that the liquid can escape through theports and to that same extent the tube will expand.

Hence it will be seen that the ports in the core are entirely responsiveto the demands of the system and will close automatically under thepressure of the tube whenever the tube approaches the ports, therebypreventing extrusion of the rubber. On the other hand, the core islikewise responsive to the increases in hydraulic pressure permittingthe outflow of the hydraulic fluid into the space between the tube andthe core. Actually the core tends naturally to assume the open positionof FIG- URE 5, due to its own resilience, when the external pressure isrelieved. Y

The outer surfaces of the tubular portions and central portion of thecore, as well as the junctures between such portions, are smooth andsharp corners have been entirely avoided so that whenever thetubecollapses it will be supported uniformly and without sharp bends. Thesolder 59 preserves the smooth outer surfaces of the walls bearing thevalve elements, and the ends of the valve elements preserve the smoothcontinuity of the outer surfaces of the Walls having the ports. Thevalve elements are primarily for the purpose of preventing extrusion ofthe rubber diaphragm through the ports, and for that reasonsubstantially fully close the ports so that hardly a crack existsbetween the heads of the valve elements and the outer surfaces of theported walls when the valve elements extend fully into the ports as inFIGURE 5. In this position, flow of liquid through the ports iseffectively blocked, although as stated, the primary purpose is toprevent extrusion of the rubber.

The perimeter of the central portion of the core is substantially equalto the inside circumference of the tube in its free state so that whencollapsed, as in FIG- URE 4, the rubber need merely flex and is notrequired to stretch. The diameter of the tube in its free state is veryclose to the inside diameter of the casing so that the tube does nothave to stretch much before it reaches the confining limit defined bythe casing 12. Hence the rubber of the tube is subjected to littlestress, confined almost wholly to exing as distinguished fromstretching, contributing to longer life.

What I claim as my invention is:

1. A backing for interiorly supporting the fiexible diaphragm tube of anaccumulator, said backing comprising a hollow core, said core includingspaced confronting walls adapted to support on their outer surfacesspaced portions of the diaphragm tube when the latter is collapsed andto tlex toward and into contact with each other by the pressure of thecollapsed tube, and means providing fiuid communication between thehollow interior of said core and the space surrounding said coreincluding a port in one of said walls, said port being substantiallyclosed by the other of said walls when said walls ex toward and intocontact with each other as aforesaid.

2. The backing defined in claim l, wherein an element is provided on theother of said walls opposed to said port and adapted to enter andsubstantially completely fill said port upon flexing of said wallstoward and into contact with each other.

3. A backing for interiorly supporting the flexible daphragm tube of anaccumulator, said backing comprising a core having a plurality ofelongated, angularly spaced tubular portions, said core having a centralportion bridging the space between said tubular portions and havingexternal surfaces shaped to blend smoothly with the external surfaces ofsaid tubular portions for the uniform support of said tube whencollapsed without sharp bends, said central portion of said coreincluding a pair of spaced confronting walls associated with eachtubular portion and extending inwardly therefrom, the walls of each pairbeing laterally spaced from each other and defining a passagecommunicating with the associated tubular portion, said walls of eachpair being adapted to support spaced portions of the tube when thelatter is collapsed and to flex toward and into contact with each otherby the pressure of the collapsed tube, and means providing uidcommunication between said passages and the space surrounding said coreincluding ports in one wall of each pair, said ports being substantiallyclosed by the other wall of each pair when said walls leX toward andinto contact with each other as aforesaid.

4. The backing defined in claim 3, wherein said core is of one-piececonstruction and is resilient, said core has at least three tubularportions and at least three pairs of confronting walls, and each wall ofeach pair of confronting walls extends into a wall of another pair andinto a Wall of its associated tubular portion.

5. The backing defined in claim 4, wherein said pairs of confrontingwalls meet at a common vertex which is the axis of said core.

6. The backing detined in claim 5, wherein the other wall of each pairis provided with elements respectively opposed to the ports in said onewall of each pair, said elements being operative to enter andsubstantially completely till said ports upon flexing of said walls ofeach pair toward and into contact with each other.

7. The backing defined in claim 6, wherein the outer surface of each ofthe said other walls is smooth, the outer surface of each of the portedwalls is smooth eX- cept for said ports and the ends of said elementslie ush with the outer surface of the ported walls when the pairs ofwalls are in contact with each other.

References Cited in the file of this patent

1. A BACKING FOR INTERIORLY SUPPORTING THE FLEXIBLE DIAPHRAGM TUBE OF ANACCUMULATOR, SAID BACKING COMPRISING A HOLLOW CORE, SAID CORE INCLUDINGSPACED CONFRONTING WALLS ADAPTED TO SUPPORT ON THEIR OUTER SURFACESSPACED PORTIONS OF THE DIAPHRAGM TUBE WHEN THE LATTER IS COLLAPSED ANDTO FLEX TOWARD AND INTO CONTACT WITH EACH OTHER BY THE PRESSURE OF THECOLLAPSED TUBE, AND MEANS PROVIDING FLUID COMMUNICATION BETWEEN THEHOLLOW INTERIOR OF SAID CORE AND THE SPACE SURROUNDING SAID COREINCLUDING A PORT IN ONE OF SAID WALLS, SAID PORT BEING SUBSTANTIALLYCLOSED BY THE OTHER OF SAID WALLS WHEN SAID WALLS FLEX TOWARD AND INTOCONTACT WITH EACH OTHER AS AFORESAID.